Over 400 Endophytic Drought-Adapted Fungi Could Reinforce Crops Against Climate Stress
- Marc Violo
- 3 hours ago
- 4 min read
Researchers isolated 415 fungal endophytes from Spain's arid Cabo de Gata region, finding that select strains can suppress up to 15 crop pathogens while simultaneously boosting plant biomass.
Dark septate endophytes showed particular promise, producing growth hormones, iron-scavenging compounds, and enzymes that improve nutrient uptake, even under saline or drought conditions.
Compatibility testing revealed that certain fungicides routinely used in horticulture are harmful to beneficial fungi, underscoring the need for integrated management strategies before field deployment.
Fungi From the Fringe of Agriculture
Mediterranean farming is facing a compounding set of pressures. Prolonged droughts are shrinking water supplies, rising temperatures are accelerating evapotranspiration, and the resulting stress on crops is increasing reliance on synthetic pesticides. Researchers at the University of Almería have been looking for answers in an unlikely quarter: the roots of plants growing in one of Europe's most inhospitable landscapes.
Between February and July 2023, a team led by Professor Mila Santos collected 68 root samples from plants adapted to the salt flats, volcanic soils, and semi-arid scrublands of Almería's Cabo de Gata Natural Park and surrounding coastal wetlands. From these samples, the team recovered 415 fungal isolates, whittling these down to 52 candidates selected for their reproductive vigour, a practical criterion given that any commercially viable bioinoculant must be mass-producible and shelf-stable.
The majority of the shortlisted fungi belonged to a group called dark septate endophytes, or DSEs. These are microscopic fungi that colonise plant roots without causing disease. They are distinguished under the microscope by their darkly pigmented, cross-walled threads (hyphae) and their capacity to form resilient resting structures called microsclerotia, which allow them to survive desiccation and nutrient scarcity. The study, published in the Journal of Plant Interactions in February 2026, assigned the isolates to eleven families within the fungal phylum Ascomycota, plus one oomycete, revealing a broader taxonomic spread than is typically found in commercially available bioformulations.
A Multifunctional Arsenal
The research tested each isolate against 15 pathogens responsible for significant losses in Mediterranean horticulture, including Verticillium dahliae, various Fusarium species, Rhizoctonia solani, and Phytophthora capsici. All isolates inhibited at least one pathogen in laboratory confrontation assays. Several Trichoderma gamsii and T. saturnisporum strains suppressed more than ten pathogens, with inhibition of V. dahliae exceeding 90% in multiple cases. These results point to the secretion of antifungal compounds and enzymes, particularly chitinases, which degrade pathogen cell walls, as the likely mechanism, a mode of action consistent with how fungal mycelia are increasingly being applied across applied biotechnology.
Beyond pathogen suppression, the fungi displayed a range of plant growth-promoting traits. Every isolate produced indole-3-acetic acid (IAA), a plant hormone that regulates root development. In the presence of the amino acid tryptophan, peak concentrations in some strains reached between 166 and 199 micrograms per millilitre after seven days. Twelve of the 29 tested isolates produced siderophores, small molecules that chelate iron from the soil and make it available to plants. Phosphate solubilisation, another key nutrient-release mechanism, was confined to strains within the genus Clarireedia, while a single T. gamsii isolate solubilised potassium. All isolates produced amylase and cellulase enzymes, indicative of their capacity to degrade complex organic matter in the root zone.
Crucially, none of the isolates caused disease symptoms when inoculated into tomato, pepper, or bean seedlings over a two-month trial. Several isolates increased total biomass significantly: in bean, certain strains produced gains of between 80% and 140% compared to uninoculated controls. These findings reinforce a growing interest in using fungal fermentation and fungal symbiosis to convert agricultural stress into productivity.
Where Chemistry and Biology Collide
One of the study's more practically significant findings concerns fungicide compatibility. Farmers routinely apply fungicides to protect crops, and any biological agent introduced alongside them must survive this chemical environment. The team tested seven commercial fungicides at multiple doses using standardised inhibition protocols.
Copper oxychloride, metrafenone, and prothioconazole were broadly harmless to the isolates. Azoxystrobin, flutriafol, and the combination of difenoconazole with cyflufenamid were predominantly toxic, inhibiting fungal growth by over 90% in many cases. Tebuconazole also proved highly inhibitory. Notably, three T. gamsii isolates showed tolerance to flutriafol across all tested doses, a finding with practical implications for integrated management.
This incompatibility question is not trivial. As endophytic fungi increasingly attract attention as low-cost solutions for crop challenges, the prospect of those fungi being neutralised by standard fungicide applications represents a real barrier to adoption. The authors call for systematic compatibility assessments and agrochemical rotation schemes as prerequisites for any field-scale deployment.
The study stops short of field validation, which remains the essential next step. Controlled conditions rarely capture the soil heterogeneity, competing microbial communities, and fluctuating climates that inoculants must navigate in practice. The isolation of specific bioactive compounds from the most promising strains, and an understanding of how these fungi behave within consortia, are also flagged as research priorities. Even so, the evidence from Almería's salt-crusted margins suggests that the fungi already quietly at work in the roots of stress-adapted plants may yet prove among agriculture's more useful allies.
